Easy Provençal Lamb

Ingredients (12)

• 1 (6- to 7-pound) bone-in leg of lamb, trimmed and tied
• 1/2 cup Dijon mustard
• 3 tablespoons chopped garlic (9 cloves), divided
• 1 tablespoon chopped fresh rosemary leaves
• 1 tablespoon balsamic vinegar
• Kosher salt and freshly ground black pepper
• 3 pounds ripe red tomatoes, cored and 1-inch-diced
• 1/2 cup good olive oil
• 1/2 cup good honey, divided
• 1 large Spanish onion, sliced
• 4 sprigs fresh thyme
• 2 sprigs fresh rosemary